1. Field of the Invention
The present invention relates to a process for preparing a plate-like artificial marble by reutilizing waste materials such as defective products of conventional industrial highly light-transmissive polymethylmethacrylate based sheets, remnants produced during product-processing and the like, including a polymethylmethacrylate based LCD (liquid crystal display) light guide panel, having a refractive index of 1.47 to 1.53 and excellent optical characteristics wherein a polymer has an average molecular weight of 30,000 to 150,000.
2. Description of the Related Art
Waste materials such as defective products, remnants produced during product-processing, and dusts produced during edge micro-processing and grinding, resulting from a preparation process of a polymethylmethacrylate based LCD light guide panel having excellent optical characteristics amount to 3,000 tons a year.
Conventionally, these materials have simply been disposed as industrial waste materials, or recovered, milled to a predetermined size and then subjected to extrusion or injection to reproduce industrial polymethylmethacrylate based sheet materials.
Further, a process for reproducing conventional industrial polymethylmethacrylate based sheet materials by recovering and washing waste materials of the conventional industrial highly light-transmissive polymethylmethacrylate based sheets and slabs, and milling them to a predetermined size, followed by extrusion or injection, was also known in the related art.
However, the above-mentioned process for reproducing sheet materials from waste materials of polymethylmethacrylate based products having excellent optical characteristics has no attractive advantage with respect to value added productivity and thus is not actively employed in the related industry.
Meanwhile, U.S. Pat. No. 6,384,101 discloses a surface treatment composition comprising an urethaneacrylate oligomer, an acrylate based monomer, a photoinitiator, a silicon additive, and silica matting agent in order to impart contamination, abrasion and scratch resistance as exhibited by marble. U.S. Pat. No. 6,440,538 discloses a laminate having a plurality of resin-impregnated layers to impart durability as exhibited by marble.
As prior arts relating to an artificial marble, U.S. Pat. No. 6,451,910 discloses an acrylic premix comprising an acrylic mono-functional monomer and a certain acrylic poly-functional monomer, which is useful for preparing an acrylic SMC (Sheet Molding Compound) having excellent high temperature-molding processability, thickening property and storage stability. U.S. Pat. No. 6,475,631 discloses an artificial marble comprising ZnO and the like, exhibiting antibacterial properties. U.S. Pat. No. 6,511,750 discloses an artificial marble comprising mica flakes, glass flakes, and the like, having an appearance remarkably resembling that of natural stone. U.S. Pat. No. 6,527,994 discloses an artificial marble having wave/wood patterns. However, the above-mentioned prior arts have focused on improvement of physical properties and appearance of the artificial marble.
In connection with the prior arts relating to a process for preparing an artificial marble using waste materials or waste resources as raw materials, Korean Patent No. 9,797 discloses a process for preparing a silicic acid-alumina-calcium oxide-alkali oxide based artificial dressed stone prepared by melting and crystallizing slag. Korean Patent No. 270,939 discloses an artificial marble and process for preparing the same, comprising the steps of finely milling waste woods such as wood flour, bamboo flour and waste substances, and waste materials such as carcasses of fish and shellfish and mixing them with a thermoplastic resin followed by molding. Additionally, Chinese Patent CN1060646, CN 1081950 and CN1227198 disclose a process for preparing an artificial marble using waste slag, waste marble and waste glass as a main raw material, respectively. However, the above-mentioned prior arts use waste materials having poor optical characteristics, and thus have a disadvantage of deteriorating physical properties and quality of the artificial marble products thus prepared.